1. Field of Disclosure
The present document relates to a superconductive coil module including a shaking coil. More specifically, the present document relates to a superconductive coil module including a shaking coil having a superconductive wire member of a high temperature superconductor for being utilized for a nuclear magnetic resonance apparatus and a magnetic resonance imaging apparatus.
2. Description of Related Technology
A superconductive coil includes a superconductive wire member consisting of a superconductive material to make a significant magnetic field around, thus to be referred as superconductor because its electrical resistance decreases to reach zero under a critical temperature. Further, a high temperature superconductor does not follow BSC theory related to the superconductor and has s superconductive property at a temperature of below 30 K.
The high temperature superconductor can be stored using liquid nitrogen instead of liquid helium as a coolant to significantly save a cooling cost for cooling the superconductor and can be adapted to an analysis equipment such as a nuclear magnetic resonance apparatus or a medical equipment such as a magnetic resonance imaging apparatus, etc.
A second generation high temperature superconductive coil includes a high temperature superconductive wire member. The high temperature superconductive wire member includes a metal substrate, a buffer layer coated on a surface of the metal substrate and a superconductive layer deposited on the buffer layer. The high temperature superconductive wire member may have a critical current density of over about 1 MA/cm2 without a current loss.
The second generation high temperature superconductive coil including the high temperature superconductive wire member can generate a radial magnetic field at the event of charge to be applicable to various technical fields.
However, in case of the second generation high temperature superconductive coil the radial magnetic field fluxes through the second generation high temperature superconductive coil such that a screening current may occur in the superconductive wire member to weaken a magnitude of the radial magnetic field. The screening current continuously flows at a peripheral portion of the superconductive wire member in case of the charging and the discharging of the superconductive coil. Therefore, the screening current which permanently flows in the superconductor coil may induce a screening current induced magnetic field which fluxed along a direction opposite to the radial magnetic field. The screening current induced magnetic field may not decrease until the coolant is removed to make the superconductive coil lose a superconductive property. In particular, as the second generation superconductive coil is repeatedly charged and discharge, the screening current induced magnetic field which remains in the superconductive coil may have effect on the central magnetic field of the superconductive coil as a whole. Thus, it is necessary to remove the screening current induced magnetic field in case of the nuclear magnetic resonance equipment or the magnetic resonance equipment.